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An analogue switch, also called a bilateral switch, is an electronic component that behaves in a similar way to a
An analogue switch, also called a bilateral switch, is an electronic component that behaves in a similar way to a relay
A relay
Electromechanical relay schematic showing a control coil, four pairs of normally open and one pair of normally closed contacts
An automotive-style miniature relay with the dust cover taken off
A relay is an electrically operated switc ...
, but has no moving parts
Machines include both fixed and moving parts. The moving parts have controlled and constrained motions.
Moving parts are machine components excluding any moving fluids, such as fuel, coolant or hydraulic fluid. Moving parts also do not include ...
. The switching element is normally a pair of MOSFET
upright=1.3, Two power MOSFETs in amperes">A in the ''on'' state, dissipating up to about 100 watt">W and controlling a load of over 2000 W. A matchstick is pictured for scale.
In electronics, the metal–oxide–semiconductor field- ...
transistor
A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch electrical signals and electric power, power. It is one of the basic building blocks of modern electronics. It is composed of semicondu ...
s, one an N-channel device, the other a P-channel device. The device can conduct analog or digital signals in either direction when on and isolates the switched terminals when off. Analogue switches are usually manufactured as integrated circuit
An integrated circuit (IC), also known as a microchip or simply chip, is a set of electronic circuits, consisting of various electronic components (such as transistors, resistors, and capacitors) and their interconnections. These components a ...
s in packages containing multiple switches (typically two, four or eight). These include the 4016 and 4066 from the 4000 series.
The control input to the device may be a signal that switches between the positive and negative supply voltages, with the more positive voltage switching the device on and the more negative switching the device off. Other circuits are designed to communicate through a serial port with a host controller in order to set switches on or off.
The signal being switched must remain within the bounds of the positive and negative supply rails which are connected to the P-MOS and N-MOS body terminals. The switch generally provides good isolation between the control signal and the input/output signals. They are not used for high voltage switching.
Important parameters of an analogue switch are:
*on-resistance: the resistance when switched on. This commonly ranges from 5 ohm
Ohm (symbol Ω) is a unit of electrical resistance named after Georg Ohm.
Ohm or OHM may also refer to:
People
* Georg Ohm (1789–1854), German physicist and namesake of the term ''ohm''
* Germán Ohm (born 1936), Mexican boxer
* Jörg Ohm (1 ...
s to a few hundred ohms.
*off-resistance: the resistance when switched off. This is typically a number of megaohms or gigaohms.
*signal range: the minimum and maximum voltages allowed for the signal to be passed through. If these are exceeded, the switch may be destroyed by excessive currents. Older types of switches can even '' latch up'', which means that they continue to conduct excessive currents even after the faulty signal is removed.
*charge injection. This effect causes the switch to inject a small electric charge
Electric charge (symbol ''q'', sometimes ''Q'') is a physical property of matter that causes it to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative''. Like charges repel each other and ...
into the signal when it switches on, causing a small spike or glitch
A glitch is a short-lived technical fault, such as a transient one that corrects itself, making it difficult to troubleshoot. The term is particularly common in the computing and electronics industries, in circuit bending, as well as among pl ...
. The charge injection is specified in coulomb
The coulomb (symbol: C) is the unit of electric charge in the International System of Units (SI).
It is defined to be equal to the electric charge delivered by a 1 ampere current in 1 second, with the elementary charge ''e'' as a defining c ...
s.
Analogue switches are available in both through-hole technology
In electronics, through-hole technology (also spelled "thru-hole") is a manufacturing scheme in which leads on the components are inserted through holes drilled in printed circuit boards (PCB) and soldered to pads on the opposite side, eithe ...
or by surface-mount technology
Surface-mount technology (SMT), originally called planar mounting, is a method in which the electrical components are mounted directly onto the surface of a printed circuit board (PCB). An electrical component mounted in this manner is referred ...
packages.
See also
*Analog-to-digital converter
In electronics, an analog-to-digital converter (ADC, A/D, or A-to-D) is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a Digital signal (signal processing), digi ...
* Telecommunications equipment
Telecommunications equipment (also telecoms equipment or communications equipment) is a type of hardware which is used for the purposes of telecommunications. Since the 1990s the boundary between telecoms equipment and IT hardware has become blurr ...
* Transmission gate
References
* Horn, Delton T. (1990). ''Analog switches: applications & projects'' (1st ed.). Blue Ridge Summit, PA: TAB Books. . {{Authority control Solid state switches